Automatic intercommunicating system



April- 5, 1937. W.'F. DAVIDSON 2,076,176

y AUTOMATIC INTERCOMMUNICATING SYSTEM 4 Filed July 5l, 1935 G) f 46 Fig. 1.

f4? 49, f fw Willian@ 1T Eat/02607@ amm Patented Apr. 6, 1937 l l Y UNITED STATES PATENT ori-ICE AUTOMATIC IN TERCOMMUNICATING SYSTEM William F. Davidson, St. Paul, Minn.

Application July 31, 1933, Serial No. 683,005

1 Claim. (Cl. 179-1) The present invention relates to an automatic the door and moved to the dotted line position intercommunicating system. shown in Figure 5, thereby closing the contacts In office buildings it is sometimes necessary for 9 and IB. the occupants of an oiiice to be absent during The circuit employed in the present embodibusiness hours, especially in some of the smaller ment of the invention is shown in Figure 1. 5 oiices, and when a customer or client calls at From a ground I3, a conductor I4 is connected such an office and all of the occupants are out, to the contact member I). From the other conthe caller may leave and take his business elsetact 9, associated therewith, a conductor I5 is where, with a consequent loss to the tenants of connected through a switch 66 and conductor 61 lo said office. to the coil of a conventional drop leaf signal It,

An object of the present invention is to make the other end of said coil being connected by an improved and simplied intercommunicating a conductor I1 to a battery I8, from which a system for office and similar use. conductor I9 is connected to ground 23. A drop In order to attain this object, there is proleaf 2l is mounted to be released upon operation .3 vided, in accordance with one feature of the of the relay IB, said drop leaf, when released,

invention, a two-way communicating system bemaking contact with a conductor 22 which is contween a central station and a plurality of selecnected to one terminal of a buzzer 23, the other tively energized substations, each of said subterminal of said buzzer being connected by a stations having automatic signal means embodied conductor 24 to a battery 25. From the other therein to be actuated by an element associated terminal of battery 25 a conductor 26 is conwith each of said substations. nected to the drop leaf 2|. 1 These and other features of the invention The microphone circuit for the microphone 2, will be more fully brought out in the followwhich is located in the ofce to be served, leads ing description and the accompanying drawing, from ground I3,through conductor I4, conductors wherein: 21 and 28 tothe microphone 2, whence a con- 2- Figure 1 is a schematic circuit drawing of an ductor 29 is connected to a contact 3U of a seautomatic intercommunicating system embodylector switch. The arm 3| of this switch is coning the present invention. nected by a conductor 32 to one terminal of the Figure 2 is a view in front elevation of a loudprimary coil 33 of a transformer. A conductor speaker used in the present invention. 34 is connected from an intermediate point of ..0

Figure 3 is a view in front elevation of a the primary coil 33 to a switch 35. From this u microphone and housing therefor. switch a conductor 36 is connected to one ter- Figure 4 is a sectional view on the line 4-4 minal of a battery 31, a conductor 38 being conof Figure 3; and nected from the other terminal of this battery Figure 5 is a fragmentary sectional view to ground 39. 35 through a door and frame thereof, showing in A secondary coil 40 is associated with the prielevation a switch mechanism mounted on the mary coil 33 to form a transformer and from door frame to be actuated by the opening of said the secondary coil 40 conductors 4I and 42 are door. connected to the input side of an audio amplier 40 Referring to the drawing in detail, a loudspeak- 43 oi a well known type. From an Output terer I is installed in a convenient location in a minal 44 of the amplier 43, a conductor 45 is room or oiiice in which the device is to be located, connected to a conductor 46 which is connected and a microphone 2 is mounted on a wall of to conductors 21 and I4 to ground I3. A conthe oiice, preferably opposite the entrance door ductor 41 is connected to the loudspeaker I, conto said oflice. This microphone is mounted in a ductor 48, a selector switch 49, conductor 53 to 45 housing 3 having an electric lamp 4 mounted output terminal 5I of the amplier 43. therein to illuminate a transparent plate 5 A headset 52 is connected by conductors 53 mounted in the front of the housing 3. and 54 to conductors 45 and 50, respectively. A trip switch 6 is mounted on a door frame 1. An end of the transformer primary coil 33 is The switch 6 comprises a support bracket 8 havconnected by a conductor 55 to a transmitter 53, 50 'ing a pair of normally open spring contact memwhich is also connected by a conductor 51 to bers 9 and I0 supported thereon. An arm II is ground 58. pivotally mounted on the bracket 8 to normally Conductors 59 and 60 are connected to the lie in the solid line position shown in Figure '1. power supply terminals 6I and 62, respectively, 55 On opening a door I2 the arm II is engaged by oi the amplier 43, and these conductors are 55 connected to a suitable supply of alterating electrical current.

A separate circuit is provided for the lamp 4, wherein conductors 63 and 64 connect the lamp 5 4 to a battery 65.

Operation When a tenant having the present arrangement installed in his office is about to leave the oflice and desires to place the mechanism in operative condition, he closes the switch 66, and opens the door I2 and walks over to the microphone. The opening of the door I2 closes the contacts 9 and I0, thereby completing a circuit l5 from ground I3, through conductor I4, contacts 9 and I0, conductor I5, switch 66, conductor 6'I, coil of the relay I6, conductor I'I, battery I8, conductor I9, to ground 20. This energizes relay I6 and drops the leaf 2l which closes the buzzer 20 circuit through conductor 22, the buzzer 23, conductor 24, battery 25, conductor 26, and the drop leaf 2I.

The operator then throws selector switches 30 and 49 to the contacts of the circuit indicated by 25 the relay I6, in a well known manner, and closes the switch 35. These three switches may all be operated as a single unit, or may be connected to a jack in a manner well known to the art.

The operator then says good morning, or 30 other suitable greeting, and pauses, the operator speaking into the transmitter 56, which is connected by conductor 51 to a ground 58, and on the other side through conductor 55, primary coil 33, conductor 34, switch 35, conductor 36, battery 35 31, conductor 38, to ground 39. The current fluctuations set up by the transmitter 56 induce currents in the secondary transformer coil 40 and are carried by the conductors 4I and 42 to the amplifier 43. From the ampliiien, the amplifier cur- -40 rents pass through conductors 45, 46, the loudspeaker I, conductor 48, switch 49, and conductor 50, the loudspeaker transmitting the message good morning to the subscribers oflice. The subscriber then speaks into the microphone 2, 45 saying, as an example, I am leaving the office now and will return in about thirty minutes.

The microphone is connected on one side by conductors 28, 21, and I4 to ground I3, and on the other side through conductors 29, the switch 50 contact 30, switch arm 3l, conductor 32, primary coil 33, conductor switch 35 conductor 36, battery 31, and conductor 38 to ground 39.

This induces an oscillating current in the secondary coil 40 which current is conducted through the amplifier 43 as above set forth to conductors 45 and 5I from whence conductors 53 and 54, respectively, carry the current to the headset 52.

The operator then opens the switches 30, 35, and 49.

If, during the absence of the tenant a caller opens the Idoor I2, the contacts 9 and I0 will be closed, thereby actuating the drop signal 2| and the buzzer 23 as above set forth. The operator then closes the switches 30, 35, and 49, and speaks linto the transmitter 56, say, as an example, Good morning, Mr. Blank is out, but will return in about thirty minutes. Will you kindly step over to the microphone on the wall in front of you and give me your message' The callers attention is directed by the illuminated panel 5 to the microphone and he steps over to the microphone and says, for example. Tell Mr. Blank, pleas-e, that Mr. Brown called and ask him to phone my oiiice when he returns.

The operator then replies, Thank you, I will tell him.

When the tenant returns he steps over to the microphone and after the operator has completed her routine greeting, the tenant speaks into the microphone 2, This is Mr. Blank, have you any messages for me? The operator then gives the tenant any messages she may have for him. The tenant opens the switch 66 and the mechanism is thereby rendered inoperative until the switch 66 is again closed.

I claim:

An automatic secretarial inter-communicating system of the class described, comprising in combination a central station having a receiver and a transmitter, a sub-station in a room remote from said central station, said sub-station having a loud speaker receiver and a microphone transmitter, switch means operable from the sub-station to connect the central station with the substation, a signal located at the central station, and signal operating means mounted in the substation and automatically operable by the entrance of a person into the sub-station to actuate said signal in the central station and secondary switch means operable from the sub-station to render said signal operating means inoperative, for the purpose set forth.

WILLIAM F. DAVIDSON. 

